I wanna try making layouts but i'm not sure how and where to start. Are you able to help me?

I wanted to make my own layout so I started looking at tutorials on youtube and stuff. I found this one tutorial that helps teach me how to change the background and stuff but I always come across errors and problems and I'm not really sure how to figure them out. I'm not sure if I followed the tutorial wrong or not but maybe you guys can help me with this :D. If youre able to reach out to me and help me with it, it would be much appreciated!!!